gms | German Medical Science

Objective: Structural white matter changes associated with certain epilepsy subtypes have been demonstrated using diffusion tensor imaging (DTI). However, so far, this has not been investigated for symptomatic seizures in glioma patients. This study aims to identify potential water diffusion abnormalities in glioma patients with associated seizures.

Methods: Prospectively recruited patients diagnosed with glioma were included in this study. DTI was performed preoperatively to measure mean diffusivity (MD) and fractional anisotropy (FA) in regions-of-interest comprising marginal tumor zone, adjacent white matter as well as distant ipsilateral and contralateral grey and white matter. Data were compared between patients with and without seizures and mean differences were tested for statistical significance. Linear regression analysis was applied to evaluate the independent influence of epilepsy on DTI changes.

Results: A total of 23 patients were included and analyzed. Seizures were present in 12 patients (52.2%). IDH mutation was present in 8 (66.7%) and 4 (36.4%) of patients with and without epilepsy, respectively. An 1p19q codeletion was detected in 6 patients (50.0%) with seizures and in 1 patient (9.1%) without seizure. There were no statistically significant differences in MD or FA of white matter or cortical areas between the two groups. In the marginal tumor area, MD was significantly lower in patients with seizures (mean±SD: 1073.6±172.8 x 10–6 mm2/s vs 1290.3±152.3 x 10–6 mm2/s, p=0.005) whereas no difference in FA was present. Linear regression analysis revealed a statistically significant influence of epilepsy (p=0.022) but not of IDH (p=0.757) or 1q19q (p=0.524) on tumor MD.

Conclusion: Tissue of the marginal tumor area appeared to be more diffusion restricted in patients with glioma associated-epilepsy. A history of seizures but not neuropathological molecular marker status independently influenced MD in the tumor area. Possibly, this may point towards a higher cellular density, cellular swelling or altered biochemical composition as an underlying pathophysiological feature of tumor associated epilepsy. No other structural changes in the white matter were observed in the presented cohort. This is possibly due to only a short history of seizures in contrast to patients treated for long standing non-tumor-associated epilepsy assuming that white matter changes might be rather the late consequence of chronic seizure activity than the cause.